KEY FACTS
Terminology
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Placenta detachment
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Most often partial and can see hematoma
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Categorized by location of abruption
Imaging
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Marginal abruption (most common)
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Hemorrhage from edge of placenta
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Retroplacental abruption (2nd most common)
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Hematoma between placenta and uterus
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May be confused for placentomegaly when acute
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Preplacental abruption (rare)
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Hematoma on fetal surface of placenta
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Hematoma appearance depends on age of blood
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Acute hematoma: Often isoechoic to placenta
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Subacute hematoma: Hypoechoic to placenta
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Resolving/chronic hematoma: Sonolucent
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Top Differential Diagnoses
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Leiomyoma: Will see flow on color Doppler
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Focal myometrial contraction: Changes during scan
Clinical Issues
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Abruption is clinical diagnosis: Only 1/3 will have findings
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Risk factors: Trauma (particularly MVA), gestational hypertension, smoking, placenta previa, prior abruption
Scanning Tips
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Use color Doppler to differentiate isoechoic clot (no flow) from placenta
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Scan entire uterus
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Hematoma may be distant from placenta edge
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Look for abruption and previa in all 2nd- and 3rd-trimester cases with vaginal bleeding or tender uterus
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Evaluate fetal heart rate early if new diagnosis of abruption
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Stop scanning and call for help if bradycardia
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Emergency cesarean warranted if viable fetus
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occurs at the placental edge. Retro-PA 
occurs between the placenta and uterine wall, and pre-PA 
occurs in front of the placenta, between the placenta and membranes.
has been lifted off the uterine wall 
. A small sonolucent hematoma is seen 
, suggesting the abruption is old. Color Doppler shows flow in the placenta and uterus but not in the clot.
